Automatic thermostat devices



June 12, 1956 c. H. STRANGE AUTOMATIC THERMOSTAT DEVICES Filed March 20,1953 IN V EN TOR. 67m 1% 55/76 STRANGE United States Patent AUTOMATICTHERMOSTAT DEVICES Charles H. Strange, White Plains, N. Y., assignor toElsa L. Strange, Jacksonville Beach, Fla.

Application March 20, 1953, Serial No. 343,731

6 Claims. (Cl. 200-137) This invention relates to new and usefulimprovements in an automatic thermostat device which has for its objectto regulate and maintain a specific predetermined temperature, or to cutoff the heat source when a specific predetermined temperature has beenattained in high temperature kilns and heat treating ovens.

For high temperatures e. g. 1,0002,000 F., there are at present manysuch heat holding and shut off controls operating from thermo-couples,which are in turn, connected to galvanometcrs that operate tuned radiofrequency circuits, photo electric electronic tubes, or minute electriccurrent high sensitive relays.

However, any or all of the above mentioned devices are expensive andcomplicated in construction and operation, and easily subject tomaladjustment or frequent breakdowns, and voltage fluctuations, whichadversely affect their efficient or precise operation.

In addition, such devices all operate from and are dependent upon athermo-couple which deteriorates rapidly and loses its calibration inhigh temperatures.

Thus the object of this invention is to provide a device for regulatingand maintaining a specific high temperature, or to cut off the source ofheat at a specific high temperature, of simple construction andoperation, which is not dependent upon a thermo-couple, and is much lessexpensive to construct and maintain than the above mentioned devices,and, in addition, more consistent in maintaining its calibration.

The inventor is well aware of the fact that there are many thermostatcontrols for lower temperatures than 1,000 F., and that the art is oldfor thermostats in this lower temperature field.

The present invention possesses distinct novelty, inasmuch as a hightemperature resistant metal strip or ribbon, such as nickel, or anickelchrome alloy, especially a patented alloy known in the trade asInconel, or an aluminum, chrome iron alloy known in the trade asKanthall is utilized as a heat expanding and lengthening unit, which isconnected to a rod so as to actuate an electric switch that requires buta very minute movement for its operation. The expanding ribbon of metalshuts off the switch and the electric current, and, when said ribboncontracts and permits the switch again to turn on the current there willbe maintained the specific heat temperature required, or the expandingribbon of metal will shut off the current at a predeterminedtemperature, and by a specially arranged switch, the current will remainoff.

The Inconel or high temperature resistant metal ribbon is stretchedacross a porcelain or metal slab of a lower coefiicient of expansionthan said ribbon and secured to the ends of said slab. Upon becomingheated the metal ribbon expands, and being securely fastened to the slabat its ends, it rises or buckles up in an outward direction from thelatter. A heat resistant metal rod is secured to the middle of the metalribbon, and at right angles to the latter, so that the rising metalribbon imparts a reciprocating motion to the rod. The rod movinglongitudinally in one direction when the metal ribbon is ex- 2,750,4'22Patented June 12, 1956 panding, and in the opposite direction when themetal ribbon is contracting, thus, accordingly operating an electricswitch by alternately turning it off or on.

With the above and other objects in view, this invention consists of thenovel features of construction, combination and arrangement of parts,hereinafter fully described, claimed and illustrated in the accompanyingdrawings forming part of this application, and in which similarcharacters of reference indicate corresponding parts in all views, andin which:

Figure 1 is a side elevation in cross section of a thermostat mechanism.

Figure 2 is a front elevation of the slab and metal ribbon.

Figure 3 is a partial cross section of a side elevation, showing thedevice installed through the wall of a kiln or heat treating oven.

Referring particularly to the drawing, the description of the saiddevice, and control of same is as follows:

The numeral 1 designates a ribbon or string of a high temperatureresistant metal secured at its ends to a porce- The numeral 6 designatesa high temperature resistant metal or ceramic tube adapted to slidablyreceive the rod 4; said tube 6 has one end secured to the slab 2 througha hole 7 at the center of the latter, and the other end by means of acoupling 16 secured to a casing or housing 8, in which an electricswitch 9 is also secured; said switch is shut off by releasing theplunger 10.

The said switch 9 is connected to a source of current (not shown) by thewires 11 and 12, and is, in turn, supported by a spring mounted holder13 secured to the housing 8. The numeral 14 shows a thread-mounted bar,which is turned by a knob 15.

In operation the metal or ceramic tube 6, containing the rod 4 andsecured to the slab 2, is inserted through the wall of the kiln or ovenfrom the inside or heating chamber and is then secured to the housing 8by means of a threaded coupling 16. The electric switch 9 is thenconnected into the electric circuit supplying the kiln heating electriccoils, or to a remote control relay, if the electric current required tooperate the oven is greater than the capacity of the switch, or theelectric switch 9 may be connected to an electric solenoid valve on thefuel line of a gas or oil heated kiln.

The threaded bar 14 is adjusted, to press against the switch holder 13and holds the switch in a predetermined position, so that the rod 4 uponbeing actuated by the expanding and contracting metal ribbon will uponexpanding of the latter, shut off the switch 9 by releasing the plunger10; while said ribbon upon contracting will cause the rod 4 to pressagainst the plunger 10 and turn on the switch 9, and thus operate thelatter at the required temperature.

It is obvious that changes may be made in the form, construction andarrangement of the several parts, as shown, within the scope of theappended claims, without departing from the spirit of the invention, andI do not, therefore Wish to limit myself to the exact construction shownand described herein.

What I claim, as new and desire to secure by Letters Patent of theUnited States, is:

1. A thermostat for temperature control comprising a ceramic slab formedwith a central opening therein, a ribbon having its ends secured to saidslab, said ribbon being of high temperature resistant metal of a highcoa ctlicient of expansion, an electric switch, a rod slidable throughsaid opening and having one end secured to the center of said ribbon ata right angle, and the other end actuating said switch.

2. A thermostat for temperature control comprising a porcelain slabformed with a central opening therein, a high temperature resistantmetal tube mounted in said slab through said opening, a ribbon havingits ends secured to said slab, said ribbon being of high temperatureresistant metal of a high coefiicient of expansion, an electric switch,a rod slidable through said metal tube and having one end secured to thecenter of said ribbon at a right angle, and the other end actuating saidswitch.

3. A thermostat for temperature control comprising a porcelain slabformed with a central opening therein, a porcelain tube mounted in saidslab through said opening, a ribbon having its ends secured to saidslab, said ribbon being of high temperature resistant metal of a highcoefficient of expansion, an electric switch, a rod slidable throughsaid porcelain tube and having one end secured to the center of saidribbon at a right angle, and the other end actuating said switch' 4. Athermostat for temperature control comprising a porcelain slab formedwith a central opening therein, a porcelain tube mounted in said slabthrough said opening, a ribbon having its ends secured to said slab,said ribbon being of high temperature resistant metal of a highcoefficient of expansion, an electric switch, a rod slidable throughsaid porcelain tube and having one end secured to the center of saidribbon at a right angle, and the other end actuating said switch, ahousing, a spring-mounted holder secured to the latter and adapted tosupport said switch.

5. A thermostat for temperature control comprising a porcelain slabformed with a central opening therein, a porcelain tube mounted in saidslab through said opening, a ribbon having its ends secured to saidslab, said ribbon being of high temperature resistant metal of a highcoeflicient of expansion, an electric switch, a rod slidable throughsaid porcelain tube and having one end secured to the center of saidribbon at a right angle, and the other end actuating said switch, ahousing, a springmounted holder secured to the latter and adapted tosupport said switch, and an adjustable threaded bar adapted to pressagainst said switch holder, whereby to secure the switch in apredetermined position, substantially as and for the purpose set forth.

6. In a device, as claimed in claim 4, and wherein said slab is nearboth ends thereof formed with slots adapted to receive the ends of saidribbon.

References Cited in the tile of this patent UNITED STATES PATENTS924,499 Rice June 8, 1909 1,443,601 Udale Jan. 30, 1923 2,313,072Hotchkiss Mar. 9, 1943 2,313,083 Malone Mar. 9, 1943 2,320,535 PetersonJune 1, 1943 2,339,087 Mantz Jan. 11, 1944 2,417,341 Arant Mar. 11, 19472,538,387 Shidler Jan. 16, 1951 FOREIGN PATENTS 490,158 Germany Jan. 24,1930

